A number of non-lethal devices exist to subdue and control an individual, a group of individuals, or a crowd. The devices are varied in type and application, and have increased in use throughout the last decade. Common devices include the bean bag projectile, various types of pepper sprays, water cannons, rubber bullets and a variety of materials fired from conventional firearms. More recently, the use of conducted electric current to incapacitate an individual has become widely used, but has been confined generally to pistol trigger-based platforms that project puncturing barbs or needles as the delivery medium of the EMI stimulus. While the effectiveness and safety of the devices vary, this stun device or “stun gun” genre has received widespread acceptance and use.
Notwithstanding the history of stun devices, there has been little improvement or change in the EMI approach. There have been few reports of biologically-based studies that characterize specific responses to stun device stimuli or to health effects of a given stun device output with reference to nerves and muscle, both of which mediate the EMI response. Very little objective laboratory data is available describing the physiological effects of stun devices. As a result of the increased usage and deployment of EMI devices, a growing number of individuals are presenting electrical injuries related to the use of such devices and a growing number of morbidities and mortalities are being observed. Understanding the physiologic effects of high voltage, variable DC current electrical injuries will allow the mechanisms contributing to the observed morbidity and mortality to be understood and devices properly evaluated for potentially injurious side effects.
Electrical discharge produces a complex set of injuries including thermal burns, cell membrane damage and rupture, and macromolecule (protein and glycosaminoglycans) denaturation or alteration. The nature and extent of the injuries appears to be related, at least in part, to the strength and duration of the discharge, its anatomic location and path through the tissues of the body, and the characteristics of the current applied (i.e., AC, DC, mixed). The organ- and organism-level effects may include skin bums, skeletal muscle death, cardiac dysrhythmia, osteocyte and osteoblast death, blood vessel endothelium dysfunction, etc. Moreover, the application of electric currents to a live subject may cause acidosis, due to incomplete or inconsistent muscular contraction. Acidosis occurs when the body is incapable of properly clearing lactic acid build-up within areas of the body, a condition that may lead to death in extreme cases. Some types of current (e.g., direct current, DC) can cause little or no injury at low levels and increasing amounts of damage and disruption of muscle control at higher levels.
One feature of typical stun devices is the expectation of instantaneous and full incapacitation upon completion of the circuit. In the prior art, the EMI stimulus was designed to elicit a fast target response, typically above the “let-go response,” after which no further increases in incapacitation are possible, other than lengthening the duration of the incapacitation while the circuit is maintained by repeated trigger pulls. In many cases, instantaneous full incapacitation may not be required or warranted, particularly in cases with vulnerable populations in which short and/or repeated periods of contact with an EMI stimulus may be preferable, or in cases where full incapacitation would put the victim at danger of falling and sustaining an injury.